skype has no more icon in system tray when I close its window. It is still active, as its notifications do appear, but I have no more access to it, cannot make calls, etc. If I close its window and try to call it again, I cannot login because it is already in use. System tray is there but only with sound and printer, and the indicator display does not show it as running.

I've removed the system tray and added it again, and even then skype does not appear. And I've uninstalled and reinstalled skype too.

sorry I did not have detailed this before.
I use Fedora 16, KDE, and skype version 4.0.0.7, which was installed using "easylife" software. But until two weeks ago there was no problem, was working normally, and skype icon was kept in system tray both when skype window was closed or not.
I think the problem occurred after some update system, because I did not install anything new app.

In fact, the same problem occurs with pidgin too (which also no longer appears in the system tray).